1. I

    Problem on Tests on mean and variance

    I need some help. It is a problem from a book called Theory of Multivariate Statistics, by Martin Bilodeau and David Brenner. It is from unit 8 (Tests on mean and variance), problem 14. Does anybody know this :)?
  2. B

    It's posible to compare two means without considering standard deviations?

    My doubt is the following 'it's possible to compare means of two independent groups without considering standard deviations" ? For example: Control Group: mean +- standard deviation 50 +- 10 mm Experimental Group: mean +- standard deviation 100 +- 30 mm I am very...
  3. C

    Assumptions for comparing means and which test to use

    I am attempting to compare the means of soil moisture measured from two adjacent soil profiles at both 10cm and 30cm. Soil measurements were measured discretely six times over the course of two months at the same date and time for each profile. However, when looking to perform tests to compare...
  4. C

    Mann Whitney U: can mean ranks be used along with medians in similarly shaped distrib

    Dear TalkStatsers, I would be deeply grateful if you could help me with a simple question I have!!! From what I have read about Mann Whitney U, it is crucial for the reporting of the results to know whether your two distributions (i.e., the distribution of scores for both groups of the...
  5. D

    Comparing whether there is a significant difference between 3 numbers. Help please!!

    Hi, So I have lots of participants for whom I have created a score for on three levels. For each participant, I am trying to find out whether there is a significant difference between the three numbers. I was thinking a one way ANOVA but as I'm doing one participant at a time, I'm not if this...
  6. T

    Reporting participant numbers for meta analysis

    Hi there, I am hoping you may be able to help me with a query I have. I am conducting a meta analysis on Random Control Trials using REVMAN. I have secondary data I am trying to input.I wanted to know whether participants are added up in each condition if there are multiple trials or whether...
  7. E

    Comparing means of frenquencies

    Hi all, Doing a comparison of keyword search frequencies and need some help determining which test to use to compare means: I was given a list of 200 keywords, and the average number of times they were searched in every month of 2014 and 2015. Took the yearly average for all 200 and want...
  8. R

    Comparing means with Poisson distributed data?

    Hi everyone! How can I perform ANOVA, so to compare means, when the data of my groups are clearly Poisson distributed (towards 0 values)? Thanks a lot! Cheers
  9. F

    Significance between samples

    I am not an expert user when it comes to SPSS so maybe this is more than I can handle. Here is the situation: I have two products I am comparing, Product A and Product B. I use the typical 7-point scale of Strongly Dislike (1) to Strongly Like (7) with Neither Like Nor Dislike (4). I recoded...
  10. B

    Determine standard deviation from percentages

    I have a normal distribution of data with a mean of 0. I know that 80% of the data falls within 3 units of the mean. So 80% of the data is from -3 to 3. How do I figure out the standard deviation? It's been a couple decades since my last math class and I'm forgetting this stuff. Thanks!
  11. E

    Comparing 2 groups of means ! shoud I use letters ?

    Hello, I hope everyone is doing well ! when comparing groups of means in a table, usually we express the differences in terms of letters next to each mean, like in the following example done by professor Gerard Dallal, which is dealing with four groups (A, B, C, D) My question now is : Can I...
  12. D

    Best way to analyze time 1/time 2 data??

    Hi There! I was hoping to get some input on the best way to test some data that I have collected (using SPSS). In short, respondents make an evaluation at time 1, then complete a distractor task, and then complete an evaluation at time 2 (DV is a 1-7 scale). It is a 2x2 between subjects...
  13. W

    Upper bound for the error on the mean for small samples.

    I have a sample of an unknown distribution for which I would like an estimate of the mean and the error on that mean. For small samples the typical way of doing this breaks down. What is a reasonable way to estimate the mean and an upper bound of the error on the mean? The error on the mean will...
  14. D

    Computing an average for a data set that contains NULL values

    Hi all! We are working on some software that shows the mean for a set of students. Currently, the calculation is being done in a manner that includes the students that haven't yet been graded. I have questioned the logic that our developers used and they have asked me to validate the...
  15. R

    Simple 4 group comparison of means problem

    I'll start by saying that I'm a neuroscience PhD student and have searched a long time for a solution to this problem but I can't find one. If you just have time to give a rough idea or point in the right direction then I'm grateful for any help. I am measuring the frequency of the same...
  16. M

    Logisti regression, mean or median of independent variable.

    Greetings great minded statisticians! I have an issue categorizing my continuous variable. I have put a continuous variable with a negative skew, into three categories. I am using logistic regression and I want to see if my three variables of omega-3 fatty acids will reduce the risk of being...
  17. F

    Descriptive Statstics Question!!

    Hey guys, I need your help: I got following question: Six customers have Tested a new chocolate bar an have rated it on 0-10 scale (10=best) . Calculate the average rating based on how often the customers go shopping and how many chocolate bars they usually buy each time they go...
  18. S

    Normal Distribution

    I cant figure out how to do this problem: I have 2 sets of means and 2 sets of SD 1sth graders scored a mean of 25 and a sd of 5 5th graders scored a mean of 30 and an sd of 10; assume the distributions are normal How do i figure out what percentage of the first graders scored better...
  19. K

    How to calculate Age-adjusted means?

    Hi, Im interested to know how to calculate age adjusted means. I know that i have to build a regression model which is adjusted by age, but after i dont have anu clue. Appreciate if someone gives an idea.
  20. S

    canceling effect of interaction in a 2-factor table of means

    Hi, I would like if there is a simple R command to get a table of means (2-factor analysis) with the interaction addendum removed (canceled out) in an ANOVA setting. thanks!